Liquid cooled saw

ABSTRACT

This invention relates to an improvement in a process for cutting a piece of wood with a cutting member directly cooled by liquid coolant. The improvement comprises using as a coolant, an aqueous dispersion of a wood treating agent selected from the group consisting of a wood preservative or colorant.

United States Patent 1 91 McDonald 51 Dec. 11, 1973 1 1 LIQUID COOLED SAW [75] Inventor: Gordon D. McDonald, Surrey, BC,

Canada [73] Assignee: SCM (Canada) Ltd., Scarborough, Ontario, Canada 22 Filed: Nov. 4, 1971 211 Appl. No.: 195,623

[52] U.S. Cl. 144/324 [51] Int. Cl B271) l/00, B27k 5/00 [58] Field of Search ..83/168, 169, 170, 83/171; 143/157 C, 158', 144/309 Y, 312,

[56] References Cited UNITED STATES PATENTS 602,943 4/1898 Hinkley 143/158 X 631,684 8/1899 Wagner 83/169 X 3,022,694 2/1962 Nuss 83/169 2,746,495 5/1956 Greenlaw 143/158 458,523 8/1891 Elliott 143/158 3,343,575 9/1967 Trout 144/34 R Primary Examiner-Andrew R. Juhasz Assistant ExaminerJames F. Coan Attorney-Merton 1-1. Douthitt [57] ABSTRACT This invention relates to an improvement in a process for cutting a piece of wood with a cutting member directly cooled by liquid coolant. The improvement comprises using as a coolant, an aqueous dispersion of a wood treating agent selected from the group consisting of a wood preservative or colorant.

7 Claims, 1 Drawing Figure LIQUID COOLED SAW In the cutting of wood with a cutting member; e.g., a saw, planer, joiner, sander, etc., the cutting member often is rotated or moved at high speed for increasing production, or it is extremely thin or find to avoid losses through the saw kerf. High speeds, especially with fine blades, tend to cause a heat build-up in the cutting member, which then often can cause scorching of the wood and fatigue or loss of temper in the cutting member. To reduce fatigue, loss of temper, and/or scorching, the cutting members typically have been directly cooled by spraying a coolant against the member.

An example of a cutting apparatus directly cooled with a coolant, but adapted for metal working is shown in U. S. Pat. No. 354,498. There, a high speed saw is cooled by ejecting cooled water against the saw blade. Another coolant, bicarbonate of soda, often is used to prevent rusting of the metal.

A process for cooling of a saw exposed to heavy pitch containing woods is shown in U. S. Pat. No. 2,746,495. A mist of pitch-dissolving solvent is sprayed against the saw blade, thereby dissolving any pitch adhering to the saw and cooling the saw blade to prevent baking of the pitch.

It is known to apply preservative and colorants to freshly cut wood for the purpose of inhibiting attack, such as from fungus, mold, mildew, and to provide color control in making wood products. Typically, the preservatives and colorants are in the form of a liquid. Treating of the wood is accomplished by spraying the wood surface with the treating agent or immersing the wood in a tank containing the liquid treating agent.

Many advantages of the process set forth herein are noted. A particular advantage is that one step in the process of preparing a wood product where the wood is cut and treated, has been eliminated. It is no longer necessary to have a separate treating stage, wherein the cut wood is contacted with preservative or colorant. As a result of the elimination of this separate treatment step, there are reduced handling requirements, elimination of processing equipment, and reduced requirement for water and raw materials. By the latter, it is meant that the water used for cooling the cutting member. and that used in making up the treating solution is combined into one unit, thereby reducing total requirements for make-up of the treating agent; and secondly, reducing the water cleaning and disposal problems.

It has been found that the above advantages are obtained in a process for cutting a piece of wood with a cutting member, cooled directly with a coolant when using as the coolant, one which is an aqueous dispersion containing a treating agent selected from the group consisting of wood preservatives and colorants.

FIG. 1 is a perspective view of an apparatus adapted for the simultaneous treatment of wood and cooling of a cutting member.

Wood preservatives and colorants useful for treating wood are known. The term, preservatives" typically is used for additives classified as pesticides, insecticides, sap stain, fungicides, and so forth for treating wood. Colorants differ from preservatives in that they are primarily pigmented and intended to alter the color of the wood, as opposed to general treatment of wood.

The treating agent; i.e., preservative or colorant is added to water and dispersed therein, usually in concentrations typically from about 0.01-10 percent by weight. The concentration, of course, is variable depending on the particular type of treating agent to be applied to the wood. Concentrations desirable for treating the wood, however, are well known and published. For example, a class of wood preservatives used to inhibit wood decaying fungi are the trialkyl tin compounds. Examples of such compounds are disclosed in U. S. Pat. No. 3,529,289 and are incorporated by reference, as they can be used here. Application of the trialkyl tin compounds to a wood surface is accomplished by dissolving in water in an amount from about 0.05-1 percent and then applying the resulting solution to the wood surface by spraying, brushing, immersing; e.g., dipping, and the like.

Sap stain solutions applied to freshly cut wood are used for maintaining a fresh cut appearance to wood and these stains are well known. Examples of sap stain control agents and adaptable for practicing this invention are set forth in U. S. Pat. No. 3,305,298 and are incorporated by reference. Examples of the common sap stain control agents are halogenated phenols; e.g., pentachlorophenol and the sodium salt thereof. Often, they are accompanied with borate buffers and mercuric compounds to control Ascocyte mold.

Treating of the freshly cut wood with the liquid treating agents usually requires a short contact time; e.g., 1-30 seconds. The aqueous dispersions readily penetrate the cut wood surface, for providing a treatment. Because of the ease in which the solution penetrates the wood surface, the amount of aqueous solution applied is controlled by regulating the flow against the cutting member. Usually, the rate is controlled so that desirable cooling of the blade is obtained. This provides a sufficient coating on the blade to wet the surface of the wood. Thus, the flow rate of coolant containing the treating agent can be regulated within large proportions as is desired in order to satisfactorily obtain a treated wood product.

Colorants useful in preparing wood products can be any of those commonly used by the wood processing industry. These colorants, like the preservatives, should be dispersible in water so that they can be formed into a liquid treating agent and applied by means of spraying onto a cutting member. The colorants typically are organic dyes, although they can be finely divided inorganic pigment.

Wood processing equipment for which this invention is adapted are any of those which have a cutting member. For example, such wood processing equipment would include all makes of saws, such as a band saw, jig saw, circular saw, joiner, planer, milling machine, and so forth. Techniques for the direct cooling of the cutting member for these types of wood processing equipment are known. For example, some are directly cooled by spraying a stream of liquid coolant onto the cutting member, some by spraying a mist of finely divided droplets, and some by passing the cutting member through a liquid bath of coolant prior to contact with the wood or by immersing the saw in liquid.

Referring to FIG. 1, log 12 is conveyed across table 13 in a direction toward circular saw blade 3. Circular saw 3 is mounted on shaft 6, and rotated at high speed for cutting the log into lumber. Coolant containing a treating agent selected from the group consisting of preservatives and colorants such as, for example, a 0.1 percent aqueous solution of tripropyltin nitrate is introduced into feed line 4. Feed line 4 passes to tee 14, wherein the feed is split into two lines about one-half going into line 5 and the other one-half into line 6. The feed then is passed through these lines and sprayed onto the sides of the circular saw blade 3 from nozzles 7 and 8, in sufficient quantity to cool the blade. The blade, as it is sprayed and cooled with liquid coolant, is also coated and as the saw rotates, the coolant containing the tripropyltin nitrate is applied to the freshly cut surface by the saw blade. Excess coolant which is not carried by the saw blade 3 to the log and applied thereto, is collected in recovery tank 9, filtered, reconstituted with additional treating agent, and recycled to make up additional feed.

What is claimed is:

1. In a process for cutting wood with a cutting member cooled directly with a liquid coolant, the improvement which comprises:

providing a coolant adapted to cool the cutting member and treat the freshly cut wood surface, said coolant being an aqueous mixture of a wood preservative consisting primarily of a sap stain. 2. The process of claim 1 wherein the sap stain is an alkali metal pentachlorophenate.

3. The process of claim 1 wherein the sap stain is pentachlorophenyl.

4. The process of claim 1 wherein the wood preservative further includes an insecticide.

5. The process of claim 1 wherein the wood preservative further includes a fungicide.

6. The process of claim 1, wherein the wood preservative further includes a bactericide.

7. The process of claim 1, where the wood preservative further includes an organic colorant.

' UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,777,794 Dated December 11, 1973 Inventor-(s) Gordon D. McDonald It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line6, for "find" should read -fine-;

Column 4, linesf7-8, "pentachl orophenyl" should read --pentachlorophenol-.

Signed and sealed this 16th day of July 1971 (SEAL) Attest:

MCCOY M. GIBSON, JR. 0. MARSHALL DANN Attesting Officer 7 Commissioner of Patents 

2. The process of claim 1 wherein the sap stain is an alkali metal pentachlorophenate.
 3. The process of claim 1 wherein the sap stain is pentachlorophenyl.
 4. The process of claim 1 wherein the wood preservative further includes an insecticide.
 5. The process of claim 1 wherein the wood preservative further includes a fungicide.
 6. The process of claim 1, wherein the wood preservative further includes a bactericide.
 7. The process of claim 1, where the wood preservative further includes an organic colorant. 